A navigation system performs travel guidance for enabling a user to easily and quickly reach the selected destination. A typical example is a vehicle navigation system where a vehicle is equipped with a navigation function to guide a driver to a destination through a calculated route. Such a navigation system detects the position of the user's vehicle, and reads out map data pertaining to an area at the current vehicle position from a data storage medium, for example, a CD-ROM (compact disc read-only memory), a DVD (digital versatile disc), or a hard disc. Typically, the navigation system displays a map image on a monitor screen to guide the user to a destination.
FIGS. 1A-1H show an example of overall procedure and screen display involved in the navigation system for route guidance to a destination. FIG. 1A shows an example of locator map screen of the navigation system when the destination is not specified. Typically, the navigation system displays a street on which the vehicle (current vehicle position VP) is running on a map image and a name of the street. Other information such as a north pointer NP, a map scale and a current time may also be illustrated on the display screen.
An example of process for specifying a destination in the navigation system through a Point of Interest (POI) search method is shown in FIG. 1B-1F. When a user selects to set a destination, the navigation system displays a “Find Destination by” screen as shown in FIG. 1B for specifying an input method for selecting the destination. The “Find Destination By” screen lists various methods for selecting the destination including “Address” for specifying the city and address of the destination, “Intersection” for specifying the names of two streets which intersect with one another, and “Point of Interest (POI)” for selecting the programmed destination based on the name, category or telephone number.
When selecting, the “Point of Interest” method in FIG. 1B, the navigation system displays selection methods of point of interest (POI) either by “Place Name” or “Place Type” in FIG. 1C. The “Place Name” is to specify a name of the intended POI, and the “Place Type” is to specify a category of the intended POI. If the “Place Type” is selected in FIG. 1C, the navigation system lists categories of POIs as shown in FIG. 1D.
FIG. 1E shows a screen when the user has selected a “Restaurant” category in the example of FIG. 1D. In this example, the screen includes a list of names of the restaurants typically sorted by distance from the current position. The user selects a particular restaurant among the restaurants in the list.
As the user selects a desired destination, as shown in FIG. 1F, and may press an “OK to Proceed” button for the navigation system to calculate an appropriate route to the destination. FIG. 1G shows an example of screen during which the navigation system calculates and determines the route to the destination. After determining the route, the navigation system starts the route guidance to the destination as shown in FIG. 1H.
FIG. 2 is a schematic view showing a map image including the calculated route to illustrate an example of situation that can arise during the route guidance in the conventional navigation system. The map image in FIG. 2 is mainly composed of interstate highways I-5 and I-80 where the destination is away on the highway I-80. The interstate highway I-5 have several points (waypoints which are typically intersections) that branch off to other roads (intersecting roads).
From the left, after 8.0 miles from the current vehicle position VP, the interstate highway I-5 intersects a road (intersecting road) that branches off at a point A. Similarly, at the 0.4 miles from the last branching off (point A), another intersecting road branches off from the interstate highway I-5 at a point B. Similarly, after 500 feet from the last branching off (point B), another intersecting road branches off from the interstate highway I-5 at a point C. At a point D, the calculated route takes the interstate highway I-80 toward the destination. As will be explained later, the situation of FIG. 2 can cause confusion when a route guidance list is displayed on the conventional navigation system.
FIG. 3 is a display example of a route guidance list which lists intersections (road names) and maneuver directions on the calculated route. The route guidance list of FIG. 3 reflects the situation of FIG. 2 which lists a plurality of entries. In the example of FIG. 3, each entry has a distance indicator 83, a maneuver icon 81, and a road (street) name indicator 85.
The distance indicator 83 shows the distance on the calculated route between the two roads that intersect with the calculated route indicated by the road name indicator 85. The distance can also be a length between the current vehicle position and the next road that intersects with the calculated route. The maneuver icon 81 provides information about maneuvering operation or direction, such as going straight, making a left turn, branching off to the right, etc. Thus, for the street “Arden Avenue” at the top of the list, the navigation system indicates there is a road named “Arden Avenue” that intersects with the calculated route at the driving distance of 1.0 miles which branches off to the right. A scroll key 71 allows the user to scroll the route guidance list to see more entries in the list.
As shown in the display example of FIG. 3, the three road name indicators 85 for the middle of the list show “I-5/SACRAMENTO”, i.e., the same road name. This occurs due to the geographical feature of the calculated route in the case of FIG. 2. Namely, as shown in FIG. 2, in the case where a road is comprised of a plurality of segments, the navigation system may recognize the road as a plurality of roads as opposed to one road.
This would cause confusion to the driver since the logical interpretation of this situation to the user is to remain on interstate highway I-5 rather than to the highway “I-5/SACRAMENTO” in a plurality of times. In other words, a plurality of entries “I-5/SACRAMENTO” consecutively in the guidance list is redundant and even confusing. Thus, there is a need of a new display method and apparatus to solve this problem by providing a simple and more intuitive manner of showing a route guidance list.